Mi-Sun Park

Yonsei University, Sŏul, Seoul, South Korea

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Publications (26)41.4 Total impact

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    ABSTRACT: Certain Escherichia coli (E. coli) strains have the ability to cause diarrheal disease. Five types of diarrheagenic E. coli have been identified, including EHEC, ETEC, EPEC, EAEC, and EIEC. To detect these five diarrheagenic types rapidly, we developed a one-step multiplex PCR (MP-PCR) assay using nine primer pairs to amplify nine virulence genes specific to the different virotypes, with each group being represented, i.e., stx1 and stx2 for EHEC, lt, sth, and stp for ETEC, eaeA and bfpA for EPEC, aggR for EAEC, and ipaH for EIEC. The PCR primers were constructed using MultAlin (http://bioinfo.genotoul.fr/multalin/multalin.html). The sensitivity and specificity of the constructed multiplex PCR primers were measured using DNA isolated from diarrheagenic E. coli strains representing each group. The limits of detection (LODs) were as follows: 5 × 10(1) cfu/ml for EHEC, 5 × 10(3) cfu/ml for ETEC expressing lt and sth, 5 × 10(4) cfu/ml for ETEC expressing stp, 5 × 10(2) cfu/ml for EPEC, 5 × 10(4) cfu/ml for EAEC, and 5 × 10(2) cfu/ml for EIEC. To confirm specificity, C. jejuni, C. perfringens, S. Typhimurium, V. parahaemolyticus, L. monocytogenes, Y. enterocolitica, B. cereus, and S. aureus were used as negative controls, and no amplification was obtained for these. Moreover, this kit was validated using 100 fecal samples from patients with diarrhea and 150 diarrheagenic E. coli strains isolated in Korea.
    Journal of Microbiology and Biotechnology 03/2014; · 1.40 Impact Factor
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    ABSTRACT: Seventy-four Shiga toxin-producing Escherichia coli (STEC) isolates belonging to the serotype O91:H21 were isolated from 1,643 asymptomatic human carriers in a STEC outbreak at Gwangju in Korea. Although the isolates did not cause any symptoms, all of them produced Shiga toxins 1 (Stx1) and 2 (Stx2). In order to determine why these strains cause no symptoms, we explored the differences in virulence potential between the asymptomatic STEC O91:H21 isolates and symptomatic STEC O91:H21 strains (ATCC 51435 and ATCC 51434). The asymptomatic STEC O91:H21 isolates showed strongly reduced cytopathic effects compared with the symptomatic strains when intact bacterial cells were used as an inoculant. Moreover, we found a reduced adherence phenotype when testing asymptomatic strains on HeLa cells. Real-time quantitative PCR results suggest that transcriptional repression of the genes encoding type-1 fimbriae occurs in the asymptomatic isolates but not in the symptomatic strains.
    Journal of Microbiology and Biotechnology 05/2013; 23(5):731-7. · 1.40 Impact Factor
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    ABSTRACT: We aimed at evaluating the virulence of atypical Shigella flexneri II:(3)4,7(8) by DNA microarray and invasion assay. We used a customized S. flexneri DNA microarray to analyze an atypical S. flexneri II:(3)4,7(8) gene expression profile and compared it with that of the S. flexneri 2b strain. Approximately one-quarter of the atypical S. flexneri II:(3)4,7(8) strain genes showed significantly altered expression profiles; 344 genes were more than two-fold upregulated, and 442 genes were more than 0.5-fold downregulated. The upregulated genes were divided into the category of 21 clusters of orthologous groups (COGs), and the "not in COGs" category included 170 genes. This category had virulence plasmid genes, including the ipa-mxi-spa genes required for invasion of colorectal epithelium (type III secretion system). Quantitative reverse-transcription polymerase chain reaction results also showed the same pattern in two more atypical S. flexneri II:(3)4,7(8) strains. Atypical S. flexneri II:(3)4,7(8) showed four times increased invasion activity in Caco-2 cells than that of typical strains. Our results provide the intracellularly regulated genes that may be important for adaptation and growth strategies of this atypical S. flexneri.
    Osong public health and research perspectives. 12/2012; 3(4):222-8.
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    ABSTRACT: Enteroaggregative Escherichia coli (EAEC) was recently reported as a major diarrheagenic pathogen in infant and adult travelers, both in developing and developed countries. EAEC strains are known to be highly resistant to antibiotics including quinolones. Therefore in this study we have determined the various mechanisms of quinolone resistance in EAEC strains isolated in Korea. For 26 EAEC strains highly resistant to fluoroquinolone, minimal inhibitory concentrations for fluoroquinolones were determined, mutations in the quinolone target genes were identified by PCR and sequencing, the presence of transferable quinolone resistance mechanism were identified by PCR, and the contribution of the efflux pump was determined by synergy tests using a proton pump inhibitor. The expression levels of efflux pump-related genes were identified by relative quantification using real-time PCR. Apart from two, all tested isolates had common mutations on GyrA (Ser83Leu and Ser87Gly) and ParC (Ser80Gln). Isolates EACR24 and EACR39 had mutations that have not been reported previously: Ala81Pro in ParC and Arg157Gly in GyrA, respectively. Increased susceptibility of all the tested isolates to ciprofloxacin and norfloxacin in the presence of the pump inhibitor implies that efflux pumps contributed to the resistance against fluoroquinolones. Expression of the efflux pump-related genes, tolC, mdfA, and ydhE, were induced in isolates EACR 07, EACR 29, and EACR 33 in the presence of ciprofloxacin. These results indicate that quinolone resistance of EAEC strains mainly results from the combination of mutations in the target enzyme and an increased expression of efflux pump-related genes. The mutations Ala81Pro in ParC and Arg157Gly in GyrA have not been reported previously the exact influence of these mutations should be investigated further.
    Osong public health and research perspectives. 12/2012; 3(4):239-44.
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    ABSTRACT: Shiga toxin-producing Escherichia coli causes bloody diarrhea and hemolytic-uremic syndrome and serious outbreaks worldwide. Here, we report the draft genome sequence of E. coli NCCP15657 isolated from a patient. The genome has virulence genes, many in the locus of enterocyte effacement (LEE) island, encoding a metalloprotease, the Shiga toxin, and constituents of type III secretion.
    Journal of bacteriology 07/2012; 194(14):3751-2. · 3.94 Impact Factor
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    ABSTRACT: Enterohemorrhagic Escherichia coli (EHEC) causes a disease involving diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome (HUS). Here we present the draft genome sequence of NCCP15647, an EHEC isolate from an HUS patient. Its genome exhibits features of EHEC, such as genes for verotoxins, a type III secretion system, and prophages.
    Journal of bacteriology 07/2012; 194(14):3747-8. · 3.94 Impact Factor
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    ABSTRACT: Enterohemorrhagic Escherichia coli causes severe food-borne disease in the guts of humans and animals. Here, we report the high-quality draft genome sequence of E. coli NCCP15658 isolated from a patient in the Republic of Korea. Its genome size was determined to be 5.46 Mb, and its genomic features, including genes encoding virulence factors, were analyzed.
    Journal of bacteriology 07/2012; 194(14):3749-50. · 3.94 Impact Factor
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    ABSTRACT: Whole genome-scale transcriptome analysis of enterohemorrhagic Escherichia coli (EHEC) O157:H7 EDL933 was performed to investigate the influence of mucin components on the EHEC gene expression. Here we report that the 732 candidate genes were differentially expressed by the presence of 0.5% porcine stomach mucin, including the 8 flagella-related genes. Quantitative real-time PCR analyses revealed that the transcription expression of the flg genes (encoding the structural components for flagella basal body) was down-regulated by the mucin components. Indeed, bacterial swarming motility was drastically reduced when grown on 0.3% trypton agar plates containing the mucin. These results imply that gastrointestinal (GI) mucin is a possible environmental signal which negatively regulates the flagellation of EHEC O157:H7 in the GI tract.
    Biochemical and Biophysical Research Communications 06/2012; 423(4):789-92. · 2.41 Impact Factor
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    ABSTRACT: In this study, we measured the drug resistance conferred by mdfA mutations in two Shigella flexneri strains. A mutant in mdfA genes was constructed by polymerase chain reaction-based, one-step inactivation of chromosomal genes. The antimicrobial susceptibility of parent and mutant strains to fluoroquinolones was determined by minimal inhibitory concentration (MICs). The △mdfA mutants were somewhat more susceptible to fluoroquinolones than the parent strains. The low level changes in MICs of the △mdfA mutants suggest that mdfA contributed the fluoroquinolone resistance in S flexneri. This finding found that the increased expression level of an MdfA efflux pump mediated fluoroquinolone resistance, but it is not likely a major effecter of higher resistance levels.
    Osong public health and research perspectives. 12/2011; 2(3):216-7.
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    ABSTRACT: Slaughterhouse workers are in direct contact with cattle nearly every day. The purpose of this study was to survey the presence and distribution of anti-Shiga toxin 1 (Stx1) immunoglobulin G (IgG) in slaughterhouse workers, enabling a study of the serologic response to this toxin while working in an area at high-risk of Stx-producing Escherichia coli (STEC) infection. One thousand seven hundred and twenty-nine serum samples from healthy slaughterhouse employees were collected and surveyed by indirect enzyme-linked immunosorbent assay (ELISA). Among the 5 slaughterhouse positions, slaughterers had the highest distribution of anti-Stx1 IgG values by an ELISA. Based on the ELISA values, 25% (433/1729) of the workers had anti-Stx1 IgG. Slaughterers, residual products handlers, inspectors, livestock hygiene controllers, and grading testers had anti-Stx1 IgG-positive rates of 28%, 25%, 20%, 19%, and 17%, respectively. The ELISA values of anti-Stx1 IgG increased with increases in the number of years worked by slaughterers, but not by residual products handlers, inspectors, livestock hygiene controllers, or grading testers. From these results, slaughterhouse workers are healthy and asymptomatic; slaughterers in particular are at high-risk for STEC exposure.
    Scandinavian Journal of Infectious Diseases 11/2011; 44(3):168-73. · 1.71 Impact Factor
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    ABSTRACT: We encountered a patient with hemolytic uremic syndrome (HUS) with persistent isolation of shiga toxin-producing Escherichia coli (STEC) for 3 weeks despite of having no clinical symptoms. STEC has been recognized as an important food-borne pathogen that causes severe diseases such as HUS. We characterized this STEC strain via a polymerase chain reaction, reverse-passive latex agglutination and the slide agglutination method. In this STEC strain, stx2 (shiga toxin), eaeA, tir, iha (adherence genes), espADB (type III secretion genes), and hlyA, ehxA, clyA (hemolysin genes) were present. The O antigen of the strain was non-typable.
    Yonsei medical journal 11/2011; 52(6):1039-43. · 0.77 Impact Factor
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    ABSTRACT: This study aimed to investigate the prevalence of antibiotic resistance in fecal Escherichia coli isolates from healthy persons and patients with diarrhea. E. coli isolates (n = 428) were obtained from fecal samples of apparently healthy volunteers and hospitalized patients with diarrhea. Susceptibility patterns of isolates to 16 antimicrobial agents were determined by agar disc diffusion. Most E. coli isolates exhibited less than 10% resistance against imipenem, cefotetan, aztreonam, cefepime, cefoxitin, amikacin and netilamicin, although greater than 65% were resistant to ampicillin and tetracycline. No significant difference in resistance rates for all tested antibiotics was found between isolates from the healthy-and diarrheal-patient groups, including for multi-drug resistance (p = 0.22). The highest number of resistant antibiotics was 12 antibiotics. No significant differences in antibiotic resistance were found among the sex and age strata for isolates from healthy individuals. However, antibiotic resistance rates to cefoxitin, cefotaxime, amikacin, and netilamicin were significantly higher in the isolates of men than those of women (p < 0.05) in isolates from patients with diarrhea. Furthermore, isolates from patients with diarrhea older than 40-years of age showed higher resistance to cefepime and aztreonam (p < 0.05). High resistance to the antibiotics most frequently prescribed for diarrhea was found in isolates from patients with diarrhea and apparently healthy individuals without any significant difference.
    Osong public health and research perspectives. 06/2011; 2(1):41-5.
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    ABSTRACT: This study was conducted to investigate the phenotypic and genotypic characteristics of Korean isolates of Cronobacter spp. (Enterobacter sakazakii). A total of 43 Cronobacter spp., including 5 clinical isolates, 34 food isolates, 2 environmental isolates, and 2 reference strains (C. sakazakii ATCC 29004 and C. muytjensii ATCC51329) were used in this study. Korean isolates of Cronobacter spp. were divided into 11 biogroups according to their biochemical profiles and 3 genomic groups based on the analysis of their 16S rRNA gene sequences. Biogroups 1 and 2 contained the majority of isolates (n=26), most of which were contained in 16S rRNA cluster 1 (n=34). Korean isolates of Cronobacter spp. showed diverse biochemical profiles. Biogroup 1 contained C. sakazakii GIHE (Gyeonggido Research Institute of Health and Environment) 1 and 2, which were isolated from babies that exhibited symptoms of Cronobacter spp. infection such as gastroenteritis, sepsis, and meningitis. Our finding revealed that Biogroup 1, C. sakazakii, is more prevalent and may be a more pathogenic biogroup than other biogroups, but the pathogenic biogroup was not represented clearly among the 11 biogroups tested in this study. Thus, all biogroups of Cronobacter spp. were recognized as pathogenic bacteria, and the absence of Cronobacter spp. in infant foods should be constantly regulated to prevent food poisoning and infection caused by Cronobacter spp.
    Journal of Microbiology and Biotechnology 05/2011; 21(5):509-14. · 1.40 Impact Factor
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    ABSTRACT: Dairy farmers perform various types of work and are in direct contact with dairy cattle nearly every day. The purpose of this study was to assess the prevalence of Shiga toxin-encoding genes (stx) among dairy farmers and to evaluate the relationship between stx and risk factors. A questionnaire developed in-house was sent to dairy farmers in Gyeonggi Province, Korea by registered mail. Researchers obtained stool samples and identified or administered the questionnaires by interview. The stool samples were examined for stx genes by polymerase chain reaction. Twenty (3.4%) of 589 stool samples from dairy farmers were stx-positive. The distribution of stx-positive stool samples revealed an increase in Shiga toxin-producing Escherichia coli infection with age, duration of work, and herd size. There was no association between stx-positive stool samples and type of work. For artificial insemination, taking a shower after work was significant, and the proportion of stx-positive dairy farmers increased as taking a shower after work decreased. Hygiene-related education to include taking a shower after sessions of artificial insemination should be considered. However, the stx-positive dairy farmers were small in number and the results should be interpreted with caution.
    Scandinavian Journal of Infectious Diseases 01/2011; 43(4):275-9. · 1.71 Impact Factor
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    ABSTRACT: To characterise the genetic and serological diversity of pathogenic Escherichia coli, we tested 111 E coli strains isolated from diarrhoeal patients in Korea between 2003 and 2006. The isolates were tested through polymerase chain reaction (PCR) and slide agglutination method for the detection of virulence genes and serotypes, respectively. To compare the expression of Shiga toxin (stx)-1 and stx2 genes, real-time quantitative reverse-transcriptase PCR and rapid exprssion assay, reversed-passive latex agglutination, were performed. Forty-nine Shiga toxin-producing E coli (STEC) strains and 62 non-STEC strains, including 20 enteropathogenic E coli, 20 enterotoxigenic E coli, 20 enteroaggregative E coli, and 2 enteroinvasive E coli were randomly chosen from the strains isolated from diarrhoeal patients in Korea between 2003 and 2006. PCR analysis indicated that locus of enterocyte effacement pathogenicity island, that is, eaeA, espADB, and tir genes were present in STEC, enteropathogenic E coli, and enteroinvasive E coli. Quorum sensing-related gene luxS was detected in most of pathogenic E coli strains. Major serotypes of the STEC strains were O157 (26%) and O26 (20%), whereas the non-STEC strains possessed various serotypes. Especially, all the strains with serotype O157 carried stx2 and the tested virulence factors. Of the STEC strains, the data of real-time quantitative reverse-transcriptase PCR and reversed-passive latex agglutination tests showed that messenger RNA- and protein expression of stx2 gene were higher than those of stx1 gene. Our results provide the epidemiological information regarding the trend of STEC and non-STEC infections in the general population and show the fundamental data in association of serotypes with virulence genes in diarrhoeagenic E coli strains from Korea.
    Osong public health and research perspectives. 12/2010; 1(1):29-35.
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    ABSTRACT: Three types of serotypically atypical Shigella flexneri strains were isolated from 2007 to 2008 in patients at the Korea National Institute of Health (NIH). These strains were characterized and compared with serologically typical S.flexneri. One type of strain either displayed nonreacting typing or grouping sera, reacting strongly only with polyB antisera, which indicates this strain is S. flexneri (polyB:un). The second type displayed reactions with one of the typing sera (IV) and did not bind any grouping sera (IV:un). The remaining type of strain displayed a plural agglutination pattern, reacted with one typing sera (II), and bound with two grouping sera (II:(3)4,7(8)). Among these atypical strains IV:un and II:(3)4,7(8) strains showed higher multi-antibiotic resistance in ampicillin, streptomycin, and trimethoprim-sulfamethoxazole than typical strains. Furthermore, all II:(3)4,7(8) strains harbored integrons. This study suggests that these multiple antibiotic-resistant atypical S. flexneri are new subserotypes of S.flexneri that await further serological classification.
    Journal of Microbiology and Biotechnology 10/2010; 20(10):1457-62. · 1.40 Impact Factor
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    ABSTRACT: We have investigated the distribution of integrons among 752 multidrug-resistant Salmonella isolates from human febrile and/or diarrheal patients during 1992-2007 and analyzed their genetic characteristics. Here, we report extensive integron analysis results within human isolates during the last 16 years. The gene or gene cassette(s) in the class 1 integrons found in the isolates were dfrA7, dfrA12-orfF-aadA2, aadA2, bla(PSE1), dfrA1-aadA1, dfrA17-aadA5, bla(OXA1)-aadA1, aadB-aadA1, aadA22, aadA1, and aac6'Ib-bla(OXA1)-aadA2. Class 2 integrons harboring dfrA1-sat2-aadA1 gene cassette were also found in four isolates. Twenty-nine isolates including one Salmonella Schleissheim isolate had two integrons harboring aadA2 and bla(PSE1) in their variable regions of 1.0 and 1.2 kb amplicons, respectively, which have been also found in Salmonella genomic island 1 (SGI1) of multidrug-resistant Salmonella Typhimurium DT104. The presence of SGI1 in Salmonella Schleissheim isolate was proved by SGI1-specific polymerase chain reaction. We first report a Salmonella Schleissheim having SGI1, Salmonella Typhimurium and Salmonella Heidelberg having the class 2 integron with dfrA1-sat2-aadA1 cassettes, Salmonella London with the aac6'Ib-bla(OXA1)-aadA2 gene cassette, Salmonella Chailey with the gene cassette of aadA22, and coexistence of two class 1 integrons carrying aadA22 and dfrA12-orfF-aadA2 in Salmonella Typhimurium.
    Foodborne Pathogens and Disease 10/2010; 8(2):319-24. · 2.28 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the relationship between the global regulatory mechanism known as quorum sensing and expression of virulence factors in Escherichia coli O157:H7. A non-polar luxS deletion was introduced into the chromosome of strain CI03J, a human clinical isolate from South Korea, to create the DeltaluxS mutant strain ML03J. Phenotypic characterization of wild-type and mutant strains demonstrated that ML03J had no obvious growth or metabolic defects on 0.2% glucose LB medium, produced a functionally-defective flagellum, and could not utilize sorbose; the biological significance of sorbose utilization is unknown. Omics-based analysis revealed the involvement of LuxS in the transcriptional activation of several flagella/chemotaxis-related genes (flhD; fliA, C, D, S, Z; cheA, Y, and Z), repression of glutamate-dependent acid resistance genes (gadAB), and expression of virulence factors including Shiga toxin, hemolysin, and SepD within the LEE pathogenicity island.
    Journal of Microbiology and Biotechnology 02/2010; 20(2):415-24. · 1.40 Impact Factor
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    ABSTRACT: The gene regulation by intrinsically curved DNA is one way for bacterial sensing of and response to environmental changes. Previously, we showed that the genetic element BNT2 upstream of the ecf (eae-positive conserved fragment) operon in the Escherichia coli O157:H7 virulence plasmid (pO157) has characteristics typical of intrinsically curved DNA, including the presence of multi-homopolymeric adenine:thymine tracts (AT tracts) and electrophoretic anomaly at 4 degrees C. Here we report that a local intrinsic curvature induced by the two phased AT tracts within the unusual promoter sequence of BNT2 played a major role for its temperature-dependent promoter activity. The base substitution of the AT tract in the spacer DNA between the -35 and the unusual -10 regions of the BNT2 promoter with non-AT tract sequence reduced intrinsic curvature slightly at 4 degrees C, but greatly affected its transcriptional activity. This implies that such a local intrinsic curvature within the unusual promoter of BNT2 is important for thermoregulation of the ecf operon.
    Biochemical and Biophysical Research Communications 01/2010; 391(4):1792-7. · 2.41 Impact Factor
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    ABSTRACT: The multi-antimicrobial resistance gene cluster and its derivatives have been detected in Salmonella genomic island 1 (SGI1), which has been identified in the Salmonella enterica serovar Typhimurium, phage types DT104, DT12, DT120, and U302, as well as other Salmonella serovars, including Agona, Paratyphi B, Albany, Meleagridis, Newport, Cerro, Derby, Dusseldorf, Infantis, Kiambu, and Emek. We acquired 53 Salmonella Typhimurium DT104 isolates from diarrheal patients in Korea. From these isolates, we identified a novel antimicrobial resistance gene cluster as an additional gene cassette in SGI1 from a multi-antimicrobial resistant isolate. The minimum inhibitory concentration for this isolate against ampicillin and chloramphenicol was two to four times higher than those for other multi-antimicrobial-resistant Salmonella Typhimurium DT104 isolates. The new antimicrobial resistance gene cluster detected in this isolate consisted of bla(PSE-1), sul1 Delta, floR, and tetR, in that order. The order of this gene cluster was shuffled as compared to that of the known In104 in SGI1. This report is, to the best of our knowledge, the first to identify and describe an additional shuffled antimicrobial resistance gene cluster in SGI1.
    Foodborne Pathogens and Disease 04/2009; 6(4):471-9. · 2.28 Impact Factor

Publication Stats

48 Citations
48 Downloads
2k Views
41.40 Total Impact Points

Institutions

  • 2012
    • Yonsei University
      Sŏul, Seoul, South Korea
  • 2011
    • Dongguk University
      • Department of Preventive Medicine
      Seoul, Seoul, South Korea
  • 2009–2011
    • National Institute of Health, Korea
      • Division of Enteric Bacterial Infections
      Cheongsong gun, North Gyeongsang, South Korea
  • 2010
    • Korea Centers for Disease Control and Prevention
      Daiden, Daejeon, South Korea